Flexible composite structure for magnetic coupling

ABSTRACT

An illustrative composite structure for magnetic coupling includes a non-rigid bendable, flexible and optionally easily bendable member such as urethane that is molded into a desired shape and embeds a pliable strip such as woven fiberglass and a series of spaced apart magnets positioned along the fiberglass strip. Some embodiments are formed to serve as magnetically coupling devices for forming voids in precast concrete, including a chamfer form, a magnetic coupler for frame and other shaped voids, and a magnetic coupler and protective plug for attachment channel inserts. Another embodiment provides coupling of other metallic objects, for example, holding of small loose parts in an abrasive blasting or other industrial processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a U.S. Nonprovisional Patent Application of pending U.S. Provisional Patent Application Ser. No. 61/579,117, filed Dec. 22, 2011, titled Flexible Composite Structure for Magnetic Coupling, which is hereby incorporated by reference in its entirety.

BACKGROUND

The present invention relates to magnetic coupling devices, and more specifically to a flexible composite structure for magnetic coupling.

Precast concrete slabs are generally poured and cured within steel or wood forms. Various features are often formed in the concrete slabs to enhance their utility, durability, and appearance. For example, one such feature is that chamfers are often formed at corners of the slabs. Forming a beveled edge, or chamfer, at corners make it easier to remove the slab from the form and reduce the sharpness of the edge at square corners. Reducing sharpness increases the strength of corners and reduces the likelihood voids will form due to the tendency of only fine aggregates to collect at sharp corners. Such chamfers are often formed by inserting a wood or steel chamfer stick having a triangular cross-section in the corner of the slab forms, thereby providing a uniform void that forms the chamfer in the corners of the concrete slab. Such chamfer sticks are held in place with double-sided tape, or pockets are formed on a bottom side and magnets attached in the pocket, or by other means. Another prior art method uses rigid plastic chamfer sticks having a central steel rod, and exposed magnets that are coupled to the rod, the rigidity causing the disadvantage of preventing the chamfer from flexing and conforming to corners.

Given that reconfigurable steel and wood forms are often used in order to provide concrete slabs of various sizes, such chamfer sticks generally cannot simply be permanently secured in place. Over multiple uses and repositioning, such wood or steel chamfers stick are often broken, bent, warped, or rusted, requiring that they be replaced. Additionally, with wavy concrete forms or chamfer sticks, gaps between the sticks and forms may need to be caulked before filled with concrete, adding to the preparation and cleanup required.

Another feature commonly found in precast concrete slabs is voids formed through or reliefs formed into the slab, for example for locating windows or other architectural features in the slab. A steel or wood frame in the size and shape of the desired void is typically used to define the void. Additionally, steel weld plates are often used to weld together concrete slabs when installed. Again, such frames and plates must be attached in position to the slab form during casting. Because the slab forms are generally made of steel, such feature forms and weld plates are often magnetically clamped into position, for example, using a loaf, bar, or button magnet such as those manufactured by TLK Precision, Inc. of Fountaintown, Ind., and available from Spillman Company of Columbus, Ohio. However, a more economical alternative to such magnets is sometimes desirable.

Yet another feature commonly found in precast concrete slabs is the inserting of hardware into the slabs. Such inserts are used to couple slabs together or to couple slabs with other architectural features. For example, one such type of inserts is metal attachment channel inserts, for example, concrete attachment channel inserts sold under the tradename Unistrut (trademark of the Unistrut Corporation of Cleveland, Ohio). attachment channel inserts provide an open metal channel on a face of a slab. The channel insert provides a convenient mechanical attachment point or axis to which to attach and secure other structures to the slab. Specifically, channel nuts can be anchored within the channel of the insert and provide a suitable connection point for other structures.

During pouring and curing of a concrete slab having such inserts, the inserts must be held in position relative to the slab form, and the slot of the channel temporarily plugged to prevent the flow of concrete from filling the slot. A typical material used as a temporary fill is expandable foam; however, such foam is not easily and completely removed from the slot.

SUMMARY

The present invention may comprise one or more of the features recited in the attached claims, and/or one or more of the following features and combinations thereof.

An illustrative composite structure for magnetic coupling includes a non-rigid, bendable, flexible member that is molded into a desired shape and embeds a pliable strip, such as a woven fiberglass tape, and a series of magnets spaced apart and positioned adjacent the pliable strip.

In one illustrative embodiment the member defines an elongate stick having a triangular cross-section between a first and second end, and a pliable strip extends from adjacent the first end to adjacent the second end.

Another illustrative composite structure includes a member that is molded into an elongate triangular cross-section between a first and second end, and the pliable strip extends from adjacent the first end to adjacent the second end.

In another illustrative embodiment the first member defines a rectangular sheet and further includes a plurality of spaced apart pliable strips, the plurality of magnets positioned adjacent a first side of each of the plurality of pliable strips.

In a further illustrative embodiment second, third, and fourth members are included, each of the first, second, third, and fourth pliable members including a pliable strip and a plurality of magnets spaced adjacent a first side of each of the pliable strips, the pliable strips and plurality of magnets embedded in each respective one of the first, second, third, and fourth members, and each of the first, second, third, and fourth members define a flat stick, and the sticks coupled to form a frame.

In yet another illustrative embodiment the member defines an elongate structure having a central portion and two flanges, the central portion having a first and second side, and two flanges coupled to opposite edges of the first side of the central portion and extending outwardly beyond the opposite edges of the central portion, and a void formed between the two flanges, the at least one pliable strips extends through the central portion and the two flanges, and the plurality of magnets are positioned within the central portion between the second side of the central portion and the at least one pliable strip.

Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed written description and drawings of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1 is a perspective view of an illustrative composite structure forming a chamfer stick according to the present invention and shown with a precast concrete mold;

FIG. 2 is a side perspective view of the chamfer stick of FIG. 1;

FIG. 3A is a cross-sectional end perspective view of the chamfer stick of FIG. 1 taken along sectional line 3A-3A in FIG. 2;

FIG. 3B is a cross-sectional side view of the chamfer stick of FIG. 1 taken along sectional line 3B-3B in FIG. 2;

FIG. 4 is a perspective view of illustrative composite structures forming a frame according to the present invention shown with the precast concrete mold and rectangular void form;

FIG. 5 is a is a top view of a portion of the illustrative composite structures forming a frame of FIG. 4;

FIG. 6 is an cross-sectional view of the composite frame of FIGS. 4 and 5 taken along sectional line 6-6 in FIG. 5;

FIG. 7 is a perspective view of an illustrative composite structure forming a rectangular sheet according to the present invention and shown with an abrasive blaster;

FIG. 8 is a cross-sectional view of the rectangular sheet of FIG. 7 taken along sectional line 8-8 in FIG. 7;

FIG. 9 is a front end perspective view of an illustrative composite structure forming a channel plug according to the present invention shown with the an attachment channel concrete insert;

FIG. 10A is a top, front end perspective view of the channel plug of FIG. 9;

FIG. 10B is a bottom, front end perspective view of the channel plug of FIG. 9;

FIG. 11 is a front end perspective view of an attachment channel concrete insert being separated from the channel plug of FIG. 9;

FIG. 12 is a back end view of an attachment channel concrete insert being separated from the channel plug of FIG. 9;

FIG. 13 is a cross-sectional end view of the channel plug of FIG. 9-12 taken along sectional line 13-13 in FIG. 10A;

FIG. 14A is an end view of the magnetic circuit of the channel plug of FIGS. 9-12;

FIG. 14B is a top view of the magnetic circuit of the channel plug of FIGS. 9-12;

FIG. 14C is a bottom perspective view of the magnetic circuit of the channel plug of FIGS. 9-12;

FIG. 15 is a perspective view illustrating a step of the illustrative process of making a composite structure in the form of a chamfer stick in a first illustrative mold according to the present invention;

FIG. 16 is a perspective view illustrating a step of the illustrative process of making a composite structure in the form of a chamfer stick according to the present invention;

FIG. 17 is a perspective view illustrating a step of the illustrative process of making a composite structure in the form of a chamfer stick according to the present invention;

FIG. 18 is a perspective view illustrating a step of the illustrative process of making a composite structure in the form of a chamfer stick according to the present invention;

FIG. 19 is a perspective view illustrating a step of the illustrative process of making a composite structure in the form of a chamfer stick according to the present invention; and

FIG. 20A and 20B is a perspective and end view, respectively, of a second illustrative mold according to the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting and understanding the principals of the invention, reference will now be made to one or more illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.

Referring to FIG. 1, a corner portion of an illustrative precast concrete mold 30 is shown. The mold 30 is used for forming precast concrete slabs (not shown) and includes a bottom sheet 34 and upright sides 36, typically formed from steel or another rigid material. Shown associated with the mold 30 is a composite structure formed as a chamfer stick 100 according to the present invention. The chamfer stick 100, also shown in FIG. 2, is sized and shaped to be positioned at corners 32 formed by adjoining mold bottom sheet 34 and upright sides 36, with side 116 against the side 36 and bottom side 114 against bottom sheet 34. The cross-section of the chamfer stick 100 resting in the corners 32, forms a void in the concrete slab, specifically a beveled edge, or chamfer, at the corners 32, providing various advantages, including reducing the sharpness of the edges of the concrete slab and enhancing durability, appearance, and ease of removal of the slab from the form.

Generally, one or more chamfer sticks 100 are used end-to-end to overly the corner 32 around the entire periphery (not shown) of the mold 30. Advantageously, because the illustrative embodiment of the chamfer stick 100 is non-rigid, flexible, bendable and can be bent about (and twisted along) a longitudinal axis 102 (FIG. 2), a single chamfer stick 100 can generally be bent in a gentle radius to conform to non-linear form corners. For tight radius corners, for example, 90 degrees such as that formed at intersection 38, for a typical desired durometer, two adjoining chamfer sticks 100 typically extend from along corners 32 of adjoining sides 36 and meet at the intersection 38. Additionally, chamfer stick 100 can be twisted along the longitudinal axis 102. Chamfer sticks 100 can be magnetic, thereby magnetically adhering to bottom sheets 34 and/or upright sides 36 that are formed from steel, or can be nonmagnetic and simply positioned in place, whether held in place by gravity, or by a permanent or releasable form of an attachment, for example an adhesive.

Referring to FIG. 3, a cross-sectional view of a chamfer stick 100 along a plane perpendicular to longitudinal axis 102 and cut through sectional line 3-3 (FIG. 2). The composite structure forming the chamfer stick 100 includes a compound 104 molded into a non-rigid, bendable, flexible member (coextensive with chamfer stick 100) than optionally can be pliable (easily bendable), a pliable strip 106 embedded within the pliable member; and a plurality of magnets 108 embedded within the pliable member and spaced adjacent (herein defined as near, including so near that it may be adjoining) an upper side 110 of the pliable strip.

Referring to FIGS. 1-3B, in the illustrative embodiment of the chamfer stick 100, the pliable strip 106 extends from adjacent a first end 101 (FIGS. 1-2) to adjacent a second end 103 (101), and the magnets 108 are periodically space at intervals 122 of about 3 inches. It is important to achieve an optimal space between the magnet 108 and the bottom right side 114 (FIG. 3) of the chamfer stick 100. For example, if there is excess space between the magnet 108 and the bottom side 114, for example, more than 0.030 inches for the exemplary durometer of urethane, the magnetic holding force available to adhere the chamfer stick 100 to the mold bottom sheet 34 is lessened. Additionally, the pliable strip 106 is located between the magnet 108 and the bottom side 114 to prevent the magnet from tearing through the bottom side, but if the space between the pliable strip 106 and the bottom side 114 is insufficient, for example, less than 0.010 inches for the exemplary durometer of urethane, the bottom side 114 of the chamfer stick 100 may tear or otherwise expose the pliable strip 106 and possibly the magnet 108.

Thus, the magnet 108 rests against a top side 110 of the pliable strip 106, and the bottom side 112 of the pliable strip is adjacent the bottom side 114 of the chamfer stick. For example, while the pliable strip 106 could be exposed on the side 114, in the illustrative embodiment, the proximity of the pliable strip 106 to the bottom side is such that the weave of the member is visible through the compound 104, as shown in FIG. 2, yet the compound fully encases the pliable strip 106 and the magnets 108.

Additionally, as shown in FIG. 3A, the pliable strip 106 and magnet 108 are also adjacent the back side 116 of the chamfer stick 100. Specifically, the pliable strip extends around an edge 109 of the magnet 108, at corner 118 of the chamfer stick 100 and adjacent and along a portion of back side 116 of the chamfer stick, and the edge 109 of the magnet 108 is against the top side 110 of the pliable strip that extends adjacent and along the back side 116 of the chamfer stick, thus preventing edge 109 of the magnet 108 from tearing through the back side 116 of the chamfer stick.

In the illustrative embodiment, the selected compound 104 is a moldable material and provides a desirable balance of pliability, strength, and durability, specifically, urethane, 60 or 90 shore “A” durometer, typically sold as “urethane rubber.” Alternatively, other compounds can be used that provide this or a different desired pliability, strength, and durability, for example, vinyl. Advantageously, because the chamfer sticks 100 can be pliable and magnetic, they conform to the contour of wavy steel forms without needing to be specifically bent into the contour or caulk used to fill gaps formed between the stick and the form.

Also in the illustrative embodiment, the pliable strip 106 is a loose weave aramid-and-fiberglass woven fabric tape or strip. The pliable strip 106 adds durability to the composite chamfer stick 100, while maintaining pliability. For example, pliable strip 106 maintains a minimum space 115 and 117 (FIG. 3A) between the magnet 108 and sides 114 and 116, minimizing the air gap between the magnet and bottom side 114, while leaving enough compound 104 and providing a structure into which the compound seeps that prevents the magnets 108 from easily breaking through the compound 104 at sides 114 or 116 when the stick 100 is bent, stretched, twisted, or compressed. The pliable strip 106 also prevents or minimizes stretching of the chamfer stick 100 along its axis 102 (FIG. 2), preventing possible breakage and reduction and deformation of the triangular cross-section of the chamfer stick.

In the illustrative embodiment for a chamfer stick having sides 114 and 116 about 0.75 inches wide, and using a woven fiberglass strip, the pliable strip 106 can be about 0.063 inches thick and about 0.75 inches wide; however, when positioned adjacent magnets 108 and molded into compound 104, the thickness of the pliable strip 106 is compressed to about 0.030 inches. This illustrative thickness minimizes the space between the magnet 108 and the bottom surface 114 of the chamfer stick while also providing sufficient strength to prevent stretching (which reduces the cross-section and thus the size of the chamfer formed) and to prevent tearing or puncturing of the urethane compound 104 caused by the embedded magnets 108, for example when the chamfer stick 100 is pulled from a steel form 34. Other woven or non-woven materials that provide the desired strength, durability, and flexibility may be substituted for woven fiberglass, including, for example, carbon fiber materials, metallic of non-metallic screen, preferably having finished edges, or non-metallic perforated pliable strip material, pliable meaning non-rigid, flexible, and easily bendable. It is preferred that the structure of the material of pliable strip 106 have openings, perforations, or other structure characteristics that allows the compound 104 to seep partly into, commingle, or fully penetrate the structure of the pliable strip so that the junction of the adjacent molded compound and pliable strip is well bonded such that it does not separate and cause a loss of structure integrity of the composite structure.

Typical chamfer sticks 100 according to the present invention have equal length right-angled sides 114 and 116 of about 0.5 to 2 inches. The chamfer sticks 100 can be as long as required for the slab being formed; however, are typically about 8 feet long between the ends 101 and 103. The type of magnets 108 used depends in part on the holding force desired and the size of the chamfer stick 100. For typical applications, rare earth permanent magnets can be used, for example, neodymium 42H magnets, which are rated usable to 248 degrees Fahrenheit, above the limit of 180 degrees Fahrenheit typical for curing precast concrete.

For a chamfer stick 100 having about 2 inch wide right-angled sides 114 and 116, the magnets 108 can be sized about 0.16×0.9×0.9 inches, and the magnetic field is oriented through the 0.16 inches dimension, meaning the opposite poles are located on opposite larger flat sides. For a chamfer stick 100 having about 0.5 inches wide right-angled sides 114 or 116, a magnet is sized about 0.11×0.265×0.8 inches, and the magnetic field is oriented through the 0.11 inches dimension. The magnets 108 are oriented within a chamfer stick 100 so that the same pole face is directed toward the same right-angled bottom side 114 of the chamfer stick 100. However, magnets 108 of other sizes can be selected to provide the holding force desired for the particular chamfer stick 100.

Other embodiments of the chamfer stick 100 lack magnets 108. In such embodiments, it is not critical that the pliable strip 106 be specifically located adjacent the bottom side 114 or a portion of the back side 116.

Referring to FIG. 4, an embodiment of the invention forming a composite frame 200 functions to magnetically couple a metal form 40 to the precast concrete form 30. For example, metal form 40 is used for forming voids through or reliefs into precast concrete, for example for locating windows or other architectural features in the concrete slab. For example, metal form 40, which is coupled to the bottom sheet 34 by the composite frame 200, can be a frame shaped form as shown in broken line style in FIG. 4.

This illustrative composite frame 200 includes four composite structures 202 a, 202 b, 202 c, 202 d, which are formed in the shape of rectangular sheets and may be integrally or separately formed, and can be non-rigid, flexible, and bendable, and optionally pliable. Like the chamfer stick 100, structures 202 a-d each include a composite material 204, one or more a pliable strips 206, and magnets 208, and are structured and formed together like and with similar materials as the chamfer stick 100 discussed above, except that the cross sections of structures 202 a-d are each rectangular rather than triangular. Referring to FIG. 5, two alternative distribution patterns of the magnets 208 can be seen through the composite material 204 in structures 202 b and 200 c, however, other distribution patterns may be used.

FIG. 6 illustrates a sectional view of a composite structure 202 a-d according to the sectional line 6-6 (FIG. 5). Revealed in the sectional view of FIG. 6 are the pliable strips 206 a and 206 b and magnets 208 embedded within the compound 204. While in the illustrative embodiment, separate pliable strips 206 a and 206 b are used on each side of for each magnet 208, a single pliable strip 206 a may be used on only one side of the magnet, and additionally or alternatively, a single pliable strip 206 a/ 206 b extending the length of each composite structure 202 a-d can also be used on one or both sides of the magnets 208. The magnets 208 are each located against a side of a pliable strip 206 a/b, which preferably extends beyond the lateral boundaries of each magnet, and the pliable strips 206 a/b are located adjacent the bottom side 214 and/or the top side 216 of the composite structures 202 a-d.

The dimensions of the composite structures 202 a-d depend on the metal form 40 or other form being coupled to the form 30; however, an example composite structure 202 a-d is about 2 inches wide, about 0.25 inches think between sides 214 and 216, and the magnets 208 are sized about 0.16×0.45×0.9 inches, and the magnetic field is oriented from the 0.16 inches dimension. While a magnetic sheet spanning the entire form 40 could be used, the advantage of using a frame 200 comprising structure 202 a-d is that the amount of magnets 208 required to hold the metal form 40 to the concrete form 30 is minimized, thus reducing the cost.

Referring to FIG. 7, an embodiment of the invention forming a composite member or holder 300 functions to magnetically couple metal parts or components 42 to the screen of an abrasive blaster 44, or other ferrous metal structure. For example, small metal parts 42 can be difficult to position and hold in place during abrasive blasting or other industrial processes. The holder 300 provides a magnetic field to secure the parts 42 to the holder 300 and the holder to the abrasive blaster 44, for example, to a metal screen 46 of the abrasive blaster.

As shown in FIG. 8, this illustrative holder 300 is formed in the shape of rectangular sheets like any of the composite structures 202 a-d discussed above, and can be non-rigid, flexible, and bendable, and optionally pliable. Like the chamfer stick 100 and structures 202 a-d, the holder 300 includes a composite material 304, one or more pliable strip 306 a and 306 b, and magnets 308, and are structured and formed together like and with similar materials as the chamfer stick 100 and structures 202 a-d discussed above, including that the cross-section of holder 300 is rectangular, as shown in FIG. 8, rather than triangular; however, other cross-sectional shapes and sheet shapes other than rectangular can be used.

FIG. 8 illustrates a sectional view of the holder 300 viewed according to the sectional line 8-8 (FIG. 7). Revealed in the sectional view of FIG. 8 are the pliable strips 306 a and 306 b and magnets 308 embedded within the compound 304. The magnets 308 are each located against a side of a pliable strip 306 a, which extends beyond the lateral boundaries of each magnet, and the pliable strips 306 a are located adjacent the bottom side 314 of the holder 300. Optionally, pliable strips 306 b are located on an opposite side of the magnets 308.

The dimensions of the holder 300 depend in part on the size of the metal parts 42 being coupled to the metal screen 46; however, an example holder 300 is about 4 inches square, about 0.25 inches thick between sides 314 and 316, and the magnets 308 are sized about 0.16×0.45×0.9 inches, and the magnetic field is oriented from the 0.16 inches dimension. A magnetic circuit 430 discussed below, or other variations of magnetic circuits, could also be used in holder 300 or frame 200.

Referring to FIGS. 9-10B, an embodiment of the invention forming a composite plug 400 that functions to magnetically couple an attachment channel concrete insert 50 to a precast concrete form 30, and to protect the insert from filling with concrete while a concrete slab (not shown) is being formed. For example, concrete insert 50 is formed into a precast concrete slab to provide a means of coupling slabs together or to couple slabs with other architectural features. The attachment channel insert 50 provides an open metal channel 52 between flanges 54 on a face of a slab (not shown). The channel 52 and flanges 54 cooperate with a fastener (not shown) to provide a convenient mechanical attachment point or axis to which to attach and secure other structures to the slab.

Referring to FIGS. 10A an 10B, the illustrative composite plug 400 includes an elongate composite structure extending between a first end 401 and a second end 403, having a central portion 414 and two flanges 416, the central portion having a top side 418 and bottom side 420, and two flanges coupled at respective connectors 422 protruding from opposite edges of the first side 418 of the central portion. The two flanges 416 extend outwardly beyond the opposite edges 422 of the central portion, and a void 424 is formed between the two flanges. The composite plug 400 can be non-rigid, flexible, and bendable, and optionally pliable.

Referring to FIG. 13, a cross-sectional end view of the plug 400 viewed according to the section line 13-13 (FIG. 10A), like the chamfer stick 100, structures 202 a-d, and holder 300, the plug 400 includes a composite material 404, a pliable strip 406, and magnetic circuit structure 430, including interleaved magnets 408 and ferrous metal plates 432, thus forming a closed magnet circuit with concrete form 30. The plug 400 is structured and formed together like and with similar materials as the chamfer stick 100, structures 202 a-d, and holder 300 discussed above.

The pliable strip 406 can extend the length of the plug 400 between the first and second ends 401 and 403. Additionally, as can be understood from FIG. 13, the pliable strip 406 extends between and into each of the flanges 416, through the respective connectors 422 and through the central portion 414 adjacent the second side 420.

The magnets 408 are spaced periodically along the length of the central portion 414 between the first and second ends 401 and 403, for example, about every inch. Additionally, the magnets 408 are each located against an upper side 410 of the pliable strip 406, and the portion of the pliable strip within the central portion 414 of the plug 400 is located adjacent the bottom side 420 of the central portion. As will be described below, the flanges 416 preferably flex relative to the central portion 414, particularly at connectors 422. The better enable the desired flexure while providing a more stable central portion 414 supporting the magnetic circuit 430, the composite material can be a dual durometer, for example, the flanges 416 being 60 durometer and the central portion 414 being 90 durometer.

The dimensions of the plug 400 depends on the attachment channel insert 400 being coupled to the form 30; however, an example plug is about 2 inches wide, about 1 inches tall, and has a central portion 414 about 1.5 inches wide and about 0.5 inches thick between sides 418 and 420.

An advantage of the cross-sectional design of the plug 400 is illustrated in the front (FIG. 11) and rear (FIG. 12) views that demonstrate that as the concrete slab (not shown) formed around the insert 50 is removed from the form 30, the opposite flanges 416 of the plug 400 are pressed inwardly within the void 424 by the opposite flanges 54, for example, flexing about the connectors 422, to allow the plug to pass between the opposite flanges 54 of the holder, thus removing the plug from within the channel 52 of the insert 50 after the concrete slab is sufficiently cured to support the insert 50.

Referring to FIG. 14A-14C, in the composite plug 400, a magnet circuit 430 can be used to provide the needed holding force for plug 430 to securely support the weight and structure of a concrete insert 50, while also minimize the amount of rare-earth permanent or other magnetic material used. For example, the illustrative magnet circuit 430 includes six magnets 408 sized about 0.110×0.265×0.800 inches, and interleaved between steel or other ferrous metal strips 432. The magnetic fields are oriented through the 0.110 inches dimension.

The metal strips 432 can have a similar thickness of about 0.110 inches, but as is best viewed in FIG. 14A, extend below the 0.8 inch dimension of the magnet, providing gaps 435 below the magnets 408 and between the strips 432, and as best viewed in FIG. 14B, extend beyond both ends of three spaced apart magnets 408 in length, providing spaces 434 between the magnets 408 and strips 432, but strips 432 having a length less than the length between ends 401 and 403 of the plug 400, as shown in FIG. 10B. As viewed in FIG. 14C, the strips 432 define through holes through the thickness that allow passage of the compound material 404 therethrough, thus retaining the magnetic circuit securely in the central portion 414 of the plug 400. As shown in FIGS. 10A and 10B, a bottom edge 444 of the ferrous metal strips 432 of the magnetic circuit 430 can be coplanar with and exposed at the bottom side 420 of the plug 400, thereby eliminating any air gap between the magnetic circuit and the concrete mold 30 to which it is magnetically attached.

FIGS. 15-19 show an illustrative process 500 of forming the illustrative composite structures 100, in this example specifically chamfer sticks, for magnetic coupling is described below. Although the illustrative process 500 relates to forming composite structure 100, it can be adapted for the other illustrative embodiments as well, including those discussed above, for example, by using a mold 550 shaped to provide the rectangular shape of other illustrative embodiments, or a mold (not shown) shaped to provide the structural shape of the plug 400.

Referring to FIG. 15, the mold 550 includes a right angle aluminum channel 552 with a steel outer layer 554 is used to mold the composite structure 100, forming the two sides 114 and 116 (FIG. 3) of the triangular cross-section. An exemplary mold 550 is about 8 feet long for forming a composite structure 100 about 8 feet long; however, molds of other desired lengths can be used.

The inside surfaces of the mold 550 are first coated with a silicone release agent, for example, Ease Release 200, available from Reynolds Advanced Materials, of LaGrange, Ill. The release agent provides for self-release of the urethane compound 104 after curing. About 10 minutes of delay is provided before beginning to assemble the composite structure 100 in the mold 550 for outgassing of the release agent.

Next, the components of the urethane compound 104 are mixed. E.g., urethane is generally provided in two components, a resin and a harder. An illustrative urethane used is 60 or 90 shore “A” durometer, with UV resistant properties, for example PMC 790 or Vytaflex 60, available from Reynolds Advance Materials, of La Grange, Ill. A colored dye may also be mixed in if desired. After mixing, the liquid urethane is degassed as needed using a vacuum.

Next, about 25% of the volume of mixed urethane used for a particular composite structure 100 is poured into the bottom of the coated mold 550, as is shown in FIG. 15. Next, the pliable strip 106 extending the full length of the mold 550 is laid onto the still liquid compound 104, also as shown in FIG. 15. The pliable strip 106 may be, for example, about 0.625 inch thick and about 0.75 inch wide woven fiberglass for the illustrative embodiment of the composite structure 100. On top of the pliable strip 106, magnets 108 are periodically placed, for example, at about 3 inch intervals for the illustrative embodiment of the composite structure 100, with polarities oriented all the same. After the magnets 108 are positioned, as shown in FIG. 16, the magnets and underlying pliable strip 106 are pressed down into the liquid urethane 104 so that the underlying member and magnets are positioned adjacent the side of the mold and the corner formed between the two sides of the mold, positioning them as shown relative to sides 114 and 116 in FIG. 3 and providing the desired minimum gaps 115 and 117 (FIG. 3A), for example about 0.030 inches. The process of pressing the strip and magnets into the liquid urethane 104 also helps to eliminate any air adjacent or between the pliable strip 106 and magnets 108.

Next, the remaining about 75% of the volume of the mixed urethane needed to form the particular illustrative composite structure 100 is poured on top of the magnets 108, pliable strip 106, and already poured urethane 104, as shown in FIG. 17. The urethane 104 is then aerated to reduce surface tension on the top of the liquid urethane and thus remove any trapped air or other gasses in the urethane.

Next, an aluminum cover 560 to complete the mold 550 is placed on top of the urethane 104, spanning the right angle aluminum channel 552 used to form the first two sides 114 and 116 of the composite structure 100, and forming the final side 120 (FIG. 3). The cover 560 can be taped in place, for example, with masking tape 564, as shown in FIG. 18. The cover 560 also includes chimneys 562, for example, at about 2 foot intervals, that allow further filling (FIG. 18) with liquid urethane to eliminate gas voids from the urethane compound 104 in the mold 550, and to allow gases to escape during the curing process.

For the initial curing, the mold 550 with the composite structure 100 to be post-cured can be next placed in a pressure chamber 570 of sufficient dimensions to enclose the mold. The initial curing speeds post-curing that otherwise could take 5-6 days, depending on the compound used and cured strength desired. For the initial curing, a pressure of about 30-50 psi is applied for about 2 to 8 hours. The length of time required for initial curing under pressure varies in part based on ambient temperature and humidity. This initial cure optionally can be completed with the pressure chamber 570 heated to an interior temperature of about 170 degrees Fahrenheit. For example, the pressure chamber 570 can be located within a temperature controlled hotbox (not shown).

After a total of about 16-24 hours, the urethane compound 104 of the composite structure 100 is sufficiently cured for the typical strength desired and illustrative compound used. The mold cover 560 can be removed and the composite structure 100 can be stripped from the mold. If the composite structure 100 is removed earlier, then the composite structure must be carefully handled and laid flat until more fully cured. Additionally or alternatively, the composite structure 100 can be post cured for about 16-24 hours at about 170 degrees Fahrenheit after the initial cure is completed; however, during post-cure, the composite structure 100 must remain in the mold 550 or be placed on a flat surface in its straight, uncurled form.

Referring to FIG. 20A and 20B, the mold 650 includes side forms 652, a bottom plate 654, and a cover plate 660 that form a void 656 can be used to mold composite structures, for example, composite structures 202 a-d and composite holder 300 discussed above. The size of the components 652, 654, 660 and void 656 of exemplary mold 650 are according to the desired dimensions of the composite structures to be formed, for example, as discussed above, and can be whatever length is desired. The process of making the composite structures 202 a-d and 300 can be the same or similar that the process described above for composite structure 100.

While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit and scope of the invention as defined in the claims and summary are desired to be protected, including, for example, that the composite member optionally can be rigid rather than non-rigid, and the strip or tape can be rigid or semi-rigid, rather than pliable. 

1. A composite structure for magnetic coupling, comprising: a compound molded into a first pliable member; at least one pliable strip embedded within the first pliable member, a structure of the at least one pliable strip allowing compound to seep into the at least one pliable strip during molding; and each of a plurality of spaced apart magnets embedded within the first pliable member and positioned adjacent a first side of the at least one pliable strip.
 2. The composite structure of claim 1, wherein the structure at least one pliable strip is woven.
 3. The composite structure of claim 1, wherein the at least one pliable strip is woven fiberglass and the compound is urethane.
 4. The composite structure of claim 1, wherein a structure of the at least one pliable strip is perforated.
 5. The composite structure of claim 1, wherein the first pliable member defines an elongate stick having a triangular cross-section between a first and second end, and the at least one pliable strip extends from adjacent the first end to adjacent the second end of the elongate stick.
 6. The composite structure of claim 5, wherein: the plurality of spaced apart magnets each: include a flat side, an opposite side, and at least one edge between the flat and opposite sides; and are magnetized through the thickness between the flat and opposite sides; and for each of the plurality of spaced apart magnets, the flat side is positioned adjacent a first side of the triangular cross-section of the elongate stick; and at least a first portion of the width of the pliable strip is positioned between the flat side and the first side of the triangular cross-section of the elongate stick.
 7. The composite structure of claim 6, wherein for each of the plurality of spaced apart magnets: the at least one edge is positioned adjacent a second side of the triangular cross-section of the elongate stick, the second side adjoining the first side, and a second portion of the width of the pliable strip extends from the flat side and is folded adjacent the at least first edge; the second portion of the width of the pliable strip is positioned between the at least first edge and the second side of the triangular cross-section of the elongate stick.
 8. The composite structure of claim 1, wherein: the first pliable member defines a sheet have a first and second side; the at least one pliable strip includes a plurality of spaced apart pliable strips; and at least a portion of the plurality of spaced apart pliable strips positioned adjacent the first side of the first pliable member; and each of the plurality of spaced apart magnets positioned adjacent a side of one of the plurality of pliable strips opposite the first side of the rectangular sheet.
 9. The composite structure of claim 1, wherein: the first pliable member defines a sheet have a first and second side; the at least one pliable strip includes a plurality of spaced apart pliable strips; a first portion of the plurality of spaced apart pliable strips positioned adjacent the first side of the first pliable member; a second portion of the plurality of spaced apart pliable strips positioned adjacent the second side of the first pliable member; and each of the plurality of spaced apart magnets positioned between ones of the plurality of pliable strips opposite the first side of the rectangular sheet.
 10. The composite structure of claim 1, wherein: the compound is further molded into a second, third, and fourth pliable members; each of the first, second, third, and fourth pliable members including at least one pliable strip and a plurality of magnets embedded within the respective pliable member and the plurality of magnets spaced apart and positioned adjacent a first side of each of the pliable strips; and each of the first, second, third, and fourth pliable members arranged to form a frame.
 11. The composite structure of claim 1, wherein: the first pliable member defines an elongate structure having a central portion and two flanges, the central portion having a top and bottom side, and two flanges coupled to opposite edges of the top side of the central portion and extending outwardly above the opposite edges of the central portion; the at least one pliable strip extends through the central portion adjacent the top side and into each of the two flanges; and the plurality of magnets are positioned within the central portion below the at least one pliable strip and adjacent the bottom side of the central portion.
 12. The composite structure of claim 11, wherein the plurality of magnets are interleaved with ferrous metal members.
 13. The composite structure of claim 12, wherein an edge of the ferrous metal members are exposed at a bottom side of the central portion of the first pliable member.
 14. A composite structure for magnetic coupling, comprising: a compound molded into a first member; at least one woven fiberglass strip embedded within the first member; and each of a plurality of magnets embedded within the first member and positioned spaced apart from one another and adjacent a first side of the at least one woven fiberglass strip.
 15. The composite structure of claim 14, wherein the first member defines an elongate non-rigid, bendable, flexible stick having a triangular cross-section between a first and second end, and the at least one woven fiberglass strip extends from adjacent the first end to adjacent the second end of the elongate stick.
 16. The composite structure of claim 15, wherein: the plurality of spaced apart magnets each: include a flat side, an opposite side, and at least one edge between the flat and opposite sides; and are magnetized through the thickness between the flat and opposite sides; and for each of the plurality of spaced apart magnets, the flat side is positioned adjacent a first side of the triangular cross-section of the elongate stick; and at least a first portion of the width of the woven fiberglass strip is positioned between the flat side and the first side of the triangular cross-section of the elongate stick.
 17. The composite structure of claim 14, wherein: the first member defines a non-rigid, bendable, flexible sheet have a first and second side; the at least one woven fiberglass strip includes a plurality of spaced apart woven fiberglass strips; and at least a portion of the plurality of spaced apart woven fiberglass strips positioned adjacent the first side of the first member; and each of the plurality of spaced apart magnets positioned adjacent a side of one of the plurality of woven fiberglass strips opposite the first side of the rectangular sheet.
 18. The composite structure of claim 14, wherein: the first member defines a non-rigid, bendable, flexible sheet have a first and second side; the at least one woven fiberglass strip includes a plurality of spaced apart woven fiberglass strips; a first portion of the plurality of spaced apart woven fiberglass strips positioned adjacent the first side of the first member; a second portion of the plurality of spaced apart woven fiberglass strips positioned adjacent the second side of the first member; and each of the plurality of spaced apart magnets positioned between ones of the plurality of woven fiberglass strips opposite the first side of the rectangular sheet.
 19. The composite structure of claim 14, wherein: the compound is further molded into a second, third, and fourth members; each of the first, second, third, and fourth members being non-rigid, bendable, flexible and including at least one woven fiberglass strip and a plurality of magnets embedded within the respective member and the plurality of magnets spaced apart and positioned adjacent a first side of each of the woven fiberglass strips; and each of the first, second, third, and fourth members arranged to form a frame.
 20. The composite structure of claim 14, wherein: the first member defines a non-rigid, bendable, flexible elongate structure having a central portion and two flanges, the central portion having a first and second side, and two flanges coupled to opposite edges of the first side of the central portion and extending outwardly beyond the opposite edges of the central portion; the at least one pliable strip extends through the central portion and the two flanges; and the plurality of magnets are positioned within the central portion between the second side of the central portion and the at least one pliable strip. 